The Portuguese boss was unimpressed by the lack of noise being generated by the Old Trafford crowd, as originally reported by the Manchester Evening News.

And Mourinho claims it wasn't until Marcus Rashford swept in the opener that he heard a roar from the home supporters.

It wasn't the first time Mourinho has slammed the Old Trafford atmosphere, having claimed it could "do better" after beating Hull in last season's EFL Cup.

Mourinho was not impressed with the Old Trafford noise (Image: Manchester United)

The crowd finally roared after Rashford's strike (Image: Getty)

Marouane Fellaini netted United's second against the Foxes to keep up the Red Devils' 100 per cent record in the Premier League.

"Rashford scored from a corner that I didn't even see because I was speaking with Lingard," Mourinho said, before he was asked for clarification over whether he saw it.

"I didn't, I was speaking with Lingard because Lingard was going to be the next player to come in when we scored the goal," Mourinho added.

"I saw the ball jumping in the net, or the guys jumping, I don't know.

"It was the first time I listen to the crowd because they were very quiet today, so it would be easy to know that was a goal because it was the first time I really understand the stadium was full."

Rashford converted in the second half (Image: Michael Regan)

Mourinho has had a pop at United supporters before (Image: REUTERS)

Mourinho reiterated United's perfect pre-season in the United States had set them up well for the new campaign.

"We had a very good pre-season," Mourinho added. "We worked really well, we had great conditions, not just to work footballistically but also to work together by being together 24 hours a day in a beautiful atmosphere in Los Angeles.

"We played against good teams, we played against the best team in Europe twice against them, the pre-season was very complete and then we start the Premier League and we are playing well."